Basic unit and test element for a mobile water analysis arrangement

ABSTRACT

A basic unit for a mobile water analyzing system includes a photometer, a test element receptacle, a photometric measuring track, and a pump actuator. The photometer comprises a light source configured to generate a measurement beam and a light detector configured to receive the measurement beam. The test element receptacle is configured so as to allow a separate test element comprising a measuring section and a pump port to be inserted into the test element receptacle. The photometric measuring track is defined by the measuring section when the separate test element is inserted into the test element receptacle. The measurement beam and the photometric measuring track are aligned during a photometric measurement so that a photometric measurement occurs along a longitudinal length of each of the photometric measuring track and the measuring section. The pump actuator is cooperatively connected with the pump port.

CROSS REFERENCE TO PRIOR APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/122,560, filed on May 10, 2011, which is a U.S National Phaseapplication under 35 U.S.C. §371 of International Application No.PCT/EP2009/062521, filed on Sep. 28, 2009 and which claims benefit toGerman Patent Application No. 10 2008 050 092.5, filed on Oct. 6, 2008.The International Application was published in German on Apr. 15, 2010as WO 2010/040655 A1 under PCT Article 21(2).

FIELD

The present invention provides a basic unit and a test element for amobile water-analyzing system for determining an analyte in awater-sample. “Mobile” means that the water-analyzing system of thepresent invention is not stationary as a continuously working processanalyzing-device.

BACKGROUND

The prior art in the field of mobile water-analysis is currentlyrepresented by so-called photometric cuvette tests as described in DE 4109 118 A1. The use of these tests is performed manually. First, awater-sample is taken by a pipette and given into the cuvette whichcontains a key-reagent. The cuvette is closed and shaken to mix thewater-sample with the key-reagent. It can then be inserted into aphotometer and measured.

The handling of such a cuvette test is inconvenient and extremelysusceptible to errors. The key-reagent used can be dangerous for healthand the environment, so that the used cuvette tests must be disposed inan appropriate way. The inconvenient handling makes the cuvette testspractical only for use in a laboratory.

SUMMARY

An aspect of the present invention is to provide a basic unit and a testelement for a mobile water-analyzing system for determining an analytein a water-sample with an improved handling.

In an embodiment, the present invention provides a basic unit for amobile water analyzing system which includes a photometer, a testelement receptacle, a photometric measuring track, and a pump actuator.The photometer comprises a light source configured to generate ameasurement beam and a light detector configured to receive themeasurement beam. The test element receptacle is configured so as toallow a separate test element comprising a measuring section and a pumpport to be inserted into the test element receptacle. The photometricmeasuring track is defined by the measuring section when the separatetest element is inserted into the test element receptacle. Themeasurement beam and the photometric measuring track are aligned duringa photometric measurement so that a photometric measurement occurs alonga longitudinal length of each of the photometric measuring track and themeasuring section. The pump actuator is cooperatively connected with thepump port.

In an embodiment, the present invention also provides a test element fora mobile water analyzing system which includes a sample line comprisingan inlet opening, a pump port, an inlet section, a measuring section,and a key reagent. The inlet opening is disposed at a first end. Theinlet opening is configured to receive a water sample. The pump port isdisposed at a second end of the sample line. The inlet section isdisposed between the inlet opening and the pump port. The measuringsection comprises at least one window arranged at an end of themeasuring section. The measuring section is arranged between the inletsection and the pump port and is coincident with a sample pathway. Thekey reagent is disposed in the sample line.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in greater detail below on the basisof embodiments and of the drawings in which:

FIG. 1 shows a schematic drawing of a mobile water-analyzing systemcomprising a basic unit and a test-element;

FIG. 2 shows the test-element of the water-analyzing system of FIG. 1;

FIG. 3 shows an embodiment of a mobile water-analyzing system includinga removable cartridge with several test-elements;

FIG. 4 shows the removable cartridge of FIG. 3;

FIG. 5 shows a front view of an embodiment of an electrochemicaltest-element;

FIG. 6 shows a rear view of the test-element of FIG. 5;

FIG. 7 shows a side view of an embodiment of a test-element with a pumpmembrane, which is controlled via a pump actuator from the basic unit;

FIG. 8 shows an embodiment of a test-element with a key-reagent and anauxiliary-reagent, whereby both reagents are arranged between an inletopening and a measuring section;

FIG. 9 shows an embodiment of a test-element with a key-reagent and aauxiliary-reagent, whereby both reagents are arranged between ameasuring section and a pump opening; and

FIG. 10 shows the test-element of FIG. 9 in a cross-sectional view inthe X-X direction.

DETAILED DESCRIPTION

In an embodiment of the present invention, the mobile water-analyzingsystem is provided with a mobile basic unit and a removable disposabletest-element which is insertable into the basic unit. The test-elementis a complex prefabricated part, whereby the test-element is providedwith a sample-line with an inlet opening which is positioned at thedistal end of the test-element. A measuring section is provided in lineof the sample-line, the sample-line being provided with a measuringtrack for an analyzer. A pump opening at the other end of thesample-line can furthermore be connected with a pump mimic of adifferent nature, the pump mimic of the basic unit comprising the pumpactuator. The water-sample can be transported in the sample-line in bothdirections and can be exactly positioned by using the pump actuator orthe pump mimic, respectively. All other parts of the analyzer can, forexample, be in the basic unit but outside of the test-element.

The test-element is furthermore provided with a key-reagent positionedinside the sample-line, the key-reagent being, for example, in a drystate. The key-reagent can be positioned between the inlet opening andthe measuring section or between the measuring section and the pumpopening.

The basic unit is provided with a test-element slot for holding theinserted test-element. The basic unit is provided with an analyzer tomeasure the water-sample inside the measuring section photometrically orelectrochemically. The basic unit is also provided with a pump actuatorwhich is connected cooperatively with the pump opening of the insertedtest-element. The pump actuator sucks the water-sample into thesample-line and transports the sucked water-sample inside thesample-line.

The determination of an analyte of a water-sample is performed by firstinserting a test-element manually or automatically into the basic unit.The inlet opening is then immersed manually into the water to beanalyzed and the pump actuator is activated. The activation can beperformed manually or automatically. By activation of the pump actuator,a water-sample is pumped through the inlet opening toward the measuringsection.

A defined volume of the water-sample is sucked and is segregated as asample-column whereby the sample column at both ends is terminated byair. By limiting the sample-column with a defined volume, a definedratio between the water-sample and the key-reagent is provided. Inaddition, by pumping the segregated water-sample column repeatedly backand forth, the water-sample is mixed with the key-reagent in thesample-line, whereby the contact of the water-sample column with thesample-line wall causes a turbulence flow, so as to provide ahomogeneous mixing of the water-sample with the key-reagent.

The limitation of the water-sample portion to a defined portion can berealized by giving the customer a signal after the pump actuator hasstopped after sucking a defined volume of the water-sample so that thecustomer obtains the information that the sampling is finished and thatthe inlet opening can be taken out of the water to be analyzed.Alternatively, the segregation of the water-sample can also be madeautomatically by using an appropriate valve which conducts air into thesample-line after the defined water-sample volume is sucked.

If the key-reagent is, seen from the inlet opening, positioned beforethe measuring section, the water-sample is mixed with the key-reagent byflowing from the inlet opening toward the measuring section.

If the key-reagent is positioned between the measuring section and thepump opening, the water-sample can be first pumped to the measuringsection to determine in a first step a background value with theanalyzer. The water-sample can thereafter be pumped to the sectionbetween the measuring section and the pump opening to react with thekey-reagent, and subsequently pumped backwards to the measuring sectionto quantitatively determine the analyte in the water-sample.

On the way from the inlet opening towards the measuring section, thewater-sample is mixed with the key-reagent in the sample-line. This canbe provided, for example, by a relatively long mixing section betweenthe key-reagent position and the measuring section. The homogenousmixing can also be intensified by pumping the mixture repeatedly backand forth through the sample-line.

The key-reagent reacts with the analyte in the water-sample so that theoptical and electrochemical properties of the water-sample change.Referring to the example of a photometrical analyzer, the absorptionspectra of the water-sample changes particularly at defined spectralines or defined spectra areas, respectively. The treated and mixedwater-sample is measured in the measuring section by the analyzer in thebasic unit electrically or optically.

The result of the measurement is evaluated and, when necessary,displayed and/or saved. As soon as the result is obtained, thetest-element can be removed manually or automatically.

The test-element can have a size of a flat match stick so that thesample-line can have a corresponding small cross-section, which is in arange between 0.01 mm² and some square millimeters. The photometricalsection or the measuring track, respectively, should be as long aspossible, for example, in the range of some millimeters to somecentimeters. Therefore, the volume of the water-sample in thephotometrical section is in the range of one to circa fifty cubicmillimeters. According to the dimensions, the amount of the key-reagentis small so that the potential danger for health and environment is alsosmall. As a consequence, the need for an appropriate disposure can beavoided so that a considerable effort for appropriate disposure orrecycling to the distributor or producer, respectively, is avoided.

All steps which are relevant for the quality of the measurement resultsof the water analysis, such as the dosage of the key-reagent, the mixingof the key-reagent with the water-sample and the waiting for thereaction time etc., are performed semi- or full-automatically,respectively, and air-tight. Errors and hazards resulting frominaccurate handling can therefore be almost completely excluded.

In an embodiment of the present invention, the disposable test-elementcan be provided with a bottom part and a separate cover part, wherebyboth parts form the sample-line therebetween. For instance, the bottompart is made out of plastic via injection die-casting whereby the bottompart is provided with an open U-shaped groove. The cover part can, forexample, be a clear-transparent plastic film which is adhered or weldedto the bottom part after all the reagents and substances have beeninserted into the sample-line. The two-part embodiment of thetest-element allows for a precise placement of the reagents andsubstances into the sample-line. This is especially so because thecross-section of the sample-line are a maximum of several squaremillimeters.

In an embodiment of the present invention, the analyzer can, forexample, be a photometer with a light source for generating ameasurement beam and a light detector for receiving the measurementbeam, whereby the measuring section which is passed through by the beamis formed by a photometer section. The photometer can, for example, beprovided as a transmission-photometer. A transmission-photometer has,compared with a reflection-photometer, a better information signal. Thetransmission-photometer allows a more precise quantitative determinationof an analyte at a relative short measuring track. The measuring sectionis provided with at least one photometrical-window for the inlet and theoutlet of the measuring beam. With the photometrical method, differentions, for example, chlorine, phosphate and ammonium, can be measured.

The analyzer can alternatively be an electrochemical analyzer whichdetermines an electrical parameter in the measuring section. Themeasuring section is provided with at least one electrode or sensorarea, respectively, which is connected through electric lines withcontacts or contact areas of the test-element, respectively. Thecontacts of the test-element are connected with the basic unit throughcontacts or through contact areas, respectively, and therefore with theanalyzer of the basic unit. The electrode or sensor area, respectively,has an area of some square micrometers to some millimeters. Differentparameters, such as conductivity, redox potential, pH-value and oxygencontent, can be measured with the electrochemical method.

The analyzer is alternatively able to measure turbidity or scattering,respectively.

The basic unit can be provided with a photometrical, an optical or anelectrochemical analyzer, respectively, so that photometrical, opticaland also electrochemical test-elements can be used alternatively via thebasic unit.

In an embodiment of the present invention, the measuring track of themeasuring section can, for example, be formed by a longitudinal sectionof the sample-line. The measuring track is thereby arranged inlongitudinal direction, not in a cross direction. In this way, themeasuring track is much longer as it would be the case if the measuringtrack would be in cross direction. The longer the measuring section, themore precise the measurement.

The test-element can be provided with a positioning element, whichprovides an exact positioning of the test-element in the basic unit. Themeasuring section of the test-element should be exactly in line with thephotometer of the basic unit to provide a photometrical measurementwithout errors. The test-element can therefore be provided with at leastone separate positioning element, which provides the positioning inaddition to the lateral surface of the test-element in the basic unit.The test-element can, for example, comprise a groove, a cavity or anopening in which a respective snap element of the basic unit snaps in,to position and fix the test-element into the basic unit.

The key-reagent can, for example, be provided in a dry state in thesample-line.

In an embodiment of the present invention, the sample-line can beprovided with an auxiliary-reagent in addition to the key-reagent. Theauxiliary-reagent can be arranged between the inlet opening and themeasuring section or between measuring section and pump opening,depending on the function.

The auxiliary-reagent can, for example be an activator which activatesthe key-reagent once the auxiliary-reagent is mixed with thewater-sample. This can improve the durability, the non-hazardous and/orthe insensibility abilities of the key-reagent.

The auxiliary-reagent can be a separate reagent which serves to analyzea second analyte in the water-sample. The auxiliary-reagent can cause amulti-stage reaction based on or after the key-reagent has reacted withthe water-sample. The support-reagent can also be an analyte-standard,which, for example, can be used to perform a standard addition.

The auxiliary-reagent can also be a neutralization-reagent which can bearranged between the measuring section and the pump opening. After thewater-sample has been analyzed in the measuring section, thewater-sample can be pumped to the auxiliary-reagent which reacts withthe key-reagent so that the key-reagent is neutralized.

The auxiliary-reagent can also gelatinize and/or color the water-sampleafter the water-sample has been analyzed. Changing the color of thewater-sample shows the customer that the test-element is used.Gelatinizing caused a fixation of the water-sample in the sample-line sothat leakage is avoided.

It is also possible to arrange numerous of different reagents in seriesin the sample-line to analyze different analysts of the samewater-sample. Once the water-sample arrives at the respective reagent,the reagent can be dissolved in the water-sample so as to react with theanalyte, for example, by changing the color. The analyte can bedetermined in the measuring section and subsequently, the water-samplecan be mixed with the second reagent to determine a second analyte inthe water-sample.

In an embodiment of the present invention, the test-element can beprovided with a pump-membrane which seals the pump opening fluid-tightand gas-tight, whereby the pump-membrane encloses a pump volume whichcan be higher than the total pump-channel volume. This allows a precisetransport and placement of the water-sample with only one stroke of thepump-membrane at the complete length of the sample-line. Thepump-membrane can be controlled via the pump actuator of the basic unit,whereby the pump actuator can be provided with a rod which pushes thepump-membrane. For example, by pushing the rod, the water-sample can bepumped backwards in direction to the inlet opening and by pulling therod, the water-sample can be pumped forward in direction to the pumpopening.

In an embodiment of the present invention, the pump actuator can, forexample, be a part of the sample-pump whereby the sample-pump isconnected with the pump opening of the inserted test-element. Allmovable parts of the sample-pump can be arranged at the basic unit. Thebasic unit and/or the test-element can provide an elastic seal in thepump opening section which provides a sealed connection between the pumpopening and the sample-pump. A gas-tight and fluid-tight connectionbetween the pump opening and the sample-pump allows for an accurate andfail-safe operation. An elastic seal provides a sealed fluidicconnection between the sample-pump and the sample-line of everytest-element. This embodiment provides an accurate and fail-safeanalyzing operation even after a long life time and after manymeasurements.

The test-element can be provided as a multi-analyte-test-element withtwo separate sample-lines with different key-reagents so that thetest-element is able to analyze two or more different analysts. Thetest-element comprises, for each analyte, a complete analyzing-mimicwhich comprises a sample-line with an inlet opening, a measuring sectionand a respective key-reagent. This allows the determination of numerousanalysts with only one measurement.

The test-element can be provided as a stripe. The stripe shapedtest-element can, for example, be made out of an elongated and flatcasting-component in which the sample-line and the measuring section isformed as a groove. The groove which forms the sample-line can be filledwith the key-reagent before the stripe is closed by a clear-transparentplastic film.

The photometer window(s) of the photometrical section can be made out ofa separate transparent window. The elongated and flat casting-componentcan alternatively be completely made out of a transparent plastic.

It is also possible to arrange numerous of the test-elements in aremovable cartridge which can be inserted into the basic unit. Thecartridge can, for example, have the shape of a drum with numerous drumchambers, whereby each drum chamber houses a test-element which isinserted air-tight. The removable cartridge allows the use of numeroustest-elements in line by using an appropriate manual, semiautomatic orfulllyautomatic load and unload mechanism.

In an embodiment of the present invention, an absorption body can, forexample, be arranged between the measuring section and the pump opening.The absorption body serves to absorb the water-sample after themeasurement has been finished and the sample has been pumped to theabsorption body. The water-sample is thereby immobilized and a leakageof the water-sample is avoided. The absorption body can, for example, bea fleece body, a clay body like bentonite or can be a so calledsuper-absorber. The body can additionally comprise a neutralizingreagent.

In an embodiment of the present invention, the sample-line can, forexample, be provided with a sample filter which filters the water-samplewhich is sucked through the inlet opening of the test-element. Thefiltration can be performed before the water-sample is transported tothe measuring section to be measured. The sample filter can be made ofmineral wool.

According to an embodiment of the present invention, the basic unit canbe provided with a heating and/or cooling element to heat or to cool thetest-element. The heating or cooling can be controlled so that anadjustment of the temperature of the test-element is possible. Atemperature of, for example, 40° C. can significantly accelerate thereaction of the key-reagent with the analyte in the water-sample or canstabilize the reaction, respectively. A cooling of the test-element orthe water-sample in the sample-line of the test-element, respectively,reduces the outgassing or the formation of disturbing gas bubbles whichcan cause errors during photometrical measurements.

In an embodiment of the present invention, the sample-line can beprovided with a hydrophobic stopper capillary. The stopper capillary canbe arranged close to the pump opening so that the stopper prevents thetransportation of the water-sample through the pump opening into thebasic unit.

According to an embodiment of the present invention, the sample-line canbe provided with a dose capillary arranged between the inlet opening andthe measuring section. The dose capillary can, for example, be arrangedadjacent to the inlet opening. By using a dose capillary, thewater-sample can be sucked, basically by the capillary force, into thetest element so that a defined water-sample volume can be segregated.The water-sample can thereafter be pumped repeatedly forth and backinside the sample-channel by using the pump actuator.

The reagent can be arranged adjacent to the inlet opening to prevent aninteraction of unreacted analyte with the sample-line wall. This isreasonable for the determination of chlorine, if the test-element or thesample-line wall is made of plastic.

The test-element can be provided with a drying agent to protect thekey-reagent against humidity. For example, the drying agent can beseparated in the sample-line by using a hydrophobic stopper capillary,whereby the humidity can flow through the stopper capillary to thedrying agent.

The inlet opening and/or the pump opening can be sealed with ahumidity-tight transport-seal, which can be opened manually orautomatically by inserting the test-element into the basic unit, forexample, by piercing. Alternatively or additionally, the singletest-element can be sealed in a humidity-tight package.

FIG. 1 and FIG. 3 schematically show a mobile water-analyzing system 10,10′ for a quantitative determination of an analyte in a water-sample.With the described embodiment of a photometrical analyzing system 10,10′ chlorine, phosphate or ammonium can be determined. Alternatively oradditionally, the analyzing system can be provided as an electrochemicalanalyzing system.

The analyzing system of FIG. 1 comprises a basic unit 14 and a removabledisposable test-element 16, which is presently inserted into the basicunit 14.

The test-element 16 is provided with a test-element body 18 made out ofplastic. The test-element body 18 has a sample-line 20 which is formedas a groove. The side with the groove opening of the test-element body18 is closed with a transparent plastic film or aluminum cover,respectively (not shown).

The sample-line 20 is provided with an inlet opening 22 which ispositioned at the distal referring to the basic unit 14 and throughwhich a water-sample is sucked from a water-reservoir 12. The distalarea of the sample-line 20 is provided with a dry key-reagent 24arranged in the sample-line 20. Adjacent to and, in the flow direction,behind the key-reagent 24 is a meander like mix section 26 of thesample-line 20 in which the key-reagent 24 and the sucked water-sampleare mixed homogeneously.

Adjacent to the mix section 26 is a measuring section 28 in which theanalyte is determined quantitatively. The present measuring section 28is a photometrical section, whereby the measuring section 28 forms ameasuring track for the respective photometrical analyzer 30 of thebasic unit 14. Both sides of the measuring section 28 comprise aclear-transparent photometrical window 44, 46 as shown in FIG. 2. Thetest-element body 18 can be completely made out of a clear transparentplastic which allows the measuring beam 35 to pass the measuring section28. The measuring track of the measuring section 28 is formed by alinear longitudinal section of the sample-line 20, i.e., the measuringtrack is running along an imaginary longitudinal axis of the sample-line20 in the measuring section 28. This provides substantially much longermeasuring track as it would be the case, if the track would run incross-direction through the sample-line 20.

At the sample-line end opposite to the inlet opening 22, a pump openingis provided 40 which is connected with a pump actuator of the samplepump of the basic unit when the test-element is inserted.

The basic unit 14 is provided with an analyzer 30 which is atransmission photometer with two light sources 32, 33 and a lightdetector 34. The light-sources 32, 33 emit light of differentwavelengths.

The basic unit 14;114 is furthermore provided with a heat and coolingelement 140 which is a peltier-element and is used to heat or to coolthe test-element (FIG. 7). The heating or cooling is controlled, so thata constant temperature of the test-element 16;116 is adjusted. Atemperature of, for example, 40° C. can significantly accelerate thereaction between an analyte in the water-sample and a key-reagent 24, orcan stabilize the reaction, respectively. A cooling of the test-element16 or the water-sample in the sample-line 20 of the test-element,respectively, reduces the outgassing or the formation of disturbing gasbubbles which cause errors during photometrical measurement.

The test-element 16 is provided with two positioning elements 48, 48′which are realized as openings. The positioning element 48, 48′cooperates with a respective snap element of the basic unit 14 so thatthe test-element 16 is fixed reproducibly and exactly. This providesthat the measuring beam 35 generated by the light source 32, 33 isexactly in line with the photometrical measuring section 28. Thetest-element receptacle of the basic unit 14 is formed as a slot 15 inwhich the test-element 16 fits without any clearance.

FIG. 3 shows an embodiment of a mobile water-analyzing system 10′including a removable cartridge 60 which is formed as a drum with 15drum chambers 62, whereby each drum chamber 62 carries a test-element16. The plastic drum body 64 is sealed axially with a circular sealingfoil 66 so that the chambers 62 are sealed gas-tight and fluid-tight.

As showed in FIG. 3, the removable cartridge 60 is inserted into arespective cartridge slot of the basic unit 14′. The basic unit 14′ isprovided with a cartridge rotary actuator 67 and a test-element shifter70. The shifter 70 can shift a test-element 16 automatically from achamber 62 into the measuring position as shown in FIG. 3.

As soon as the measurement is finished, the shifter 70 moves thetest-element 16 out of the measuring position and ejects it out of thebasic unit 14′. In a next step, the shifter 70 is completely removedfrom the cartridge 60. The rotary actuator 67 then turns the cartridge60 by one chamber angle so that the next chamber 62 with thetest-element 16 is in line with the shifter 70. As soon as a measurementrequest is signalized by the customer, the shifter 70 moves thetest-element 16 from the chamber 62 into the measuring position so thatthe measurement can start.

FIG. 5 and FIG. 6 show the respective front view and the rear view oftwo embodiments of a test-element 80. The test-element 80 is anelectrochemical test-element which is provided with an electrochemicalmeasuring section 82 in the sample-line 84. The measuring section 82 isprovided with two electrodes 86, 88 in positioned opposed to each other,the electrodes being connected through electric lines 90, 92 withcontacts 94, 96. The contacts 94, 96 are arranged in line to respectivecontacts of the basic unit whereby the contacts are connected with theelectrochemical analyzer of the basic unit.

The rear view of the test-element in FIG. 6 shows the pump opening 40. Acircular seal element 41 is provided surrounding the pump opening 40 toprovide a vacuum-tight connection between the sample-line 84 and asample-pump realized as a pump actuator 42.

FIG. 7 schematically shows a side view of a part of an embodiment of amobile water-analyzing system 10″. The water-analyzing system 10″ isprovided with a disposable test-element 116 which is provided with aconvex and vesicular pump membrane 118 above the pump opening 40. Thepump element which is formed as a pump membrane 118 has a pump volumewhich is higher as the total volume of the sample-line 84.

The basic unit 114 is provided with a pump actuator 120 with a motor 122whereby the pump actuator 120 controls a rod 124. The rod 124 pushesagainst the pump membrane 118 of the inserted disposable test-element116. The water-sample can be moved over the complete length of thesample-line forward and backward by the rod 124 deforming the pumpmembrane 118.

To determine an analyte in a water-sample, first a test-element 16 isinserted into the test-element receptacle 15 of the basic unit 14. Thiscan, if given, activate the basic unit 14. In a next step, the inletopening 22 of the test-element is immersed manually into the analyzingwater-reservoir 12 so that the sample-pump 42 sucks a water-sample intothe measuring section 28 of the sample-line 20. The analyzer 30determines the background signal of the water-sample in the measuringsection.

As soon as the background signal determination is finished, thewater-sample is pumped forward from the measuring section 28 into thereagent section 23. The water-sample meets with the key-reagent 24 inthe reagent section 23 so that the key-reagent 24 is mixed with thewater-sample. The key-reagent 24 reacts with the analyte in thewater-sample so that the optical properties of the water-sample change.

By pumping backwards, the water-sample flows back from reagent section23 to the measuring section 28. The water-sample is analyzedphotometrically by the analyzer 30. The result of the measurement is agross-value. Subtracting the background from the gross-value leads to anet concentration of the analyte in the water-sample.

With the test-element 80 of FIG. 5 and FIG. 6, an even more precisedetermination of the analyte in a water-sample can be realized by usingstandard addition. After the determination of the analyte in themeasuring section 82, the water-sample is pumped again forward to thesection with the support-reagent 25, whereby the water-sample is mixedwith the first auxiliary-reagent 27 which forms a first analytestandard.

The water-sample is then pumped backwards from the section with theauxiliary-reagent 25 into the measuring section 82, whereby thewater-sample is analyzed again photometrically. The water-sample istransported again forward to the section with the secondauxiliary-reagent 29, whereby the water-sample is mixed with the secondauxiliary-reagent 31 which forms a second analyte standard. Finally, thewater-sample is transported again backwards from the section with thesecond auxiliary-reagent to the measuring section, whereby thewater-sample is measured by the photometer.

Both photometrical analyte standard measurements lead to aconcentration-absorption characteristic line which allows an exactdetermination of the analyte concentration of the water-sample by usingthe net concentration value.

FIG. 8 shows an embodiment of a test-element 130 in which thekey-reagent 132 is arranged close to the inlet opening 22. Thispositioning of the key-reagent 132 is particularly useful for a chlorinereagent to prevent a reaction of the analyte chlorine with the plasticwall of the sample-line 20. The sample-line 20 or the complete body ofthe test-element 130, respectively, is made out of a material inert forchlorine, such as polystyrene.

Between the measuring section 28 and the pump opening 40, an auxiliaryreagent 134 is provided. The auxiliary reagent 134 can be a separatereagent for analyzing a second analyte in the water-sample. Theauxiliary reagent 134 can cause a multi-stage reaction with thewater-sample, based on or after the key-reagent 132 has reacted with thewater-sample. The auxiliary-reagent 134 can also be an analyte-standardwhich, for example, can be used to provide a standard addition.

The auxiliary-reagent 134 can also be a neutralization-reagent. Afterthe water-sample has been analyzed in the measuring section 28, thewater-sample is transported to the auxiliary-reagent 134, which reactswith the key-reagent 132. The key-reagent 132 is neutralized so that thetest-element can be disposed in the community waste.

The auxiliary-reagent 134 can also gelatinize and/or color thewater-sample after the water-sample has been analyzed. Changing thecolor of the water-sample shows the customer that the test-element 130has been used. By gelatinizing, the water-sample is fixed in thesample-line 20 so that the water-sample cannot leak.

FIG. 9 shows an embodiment of the test-element 140. The key-reagent 142and the auxiliary-reagent 144 are positioned relatively close to eachother between the inlet opening 22 and the measuring section 28. Forinstance, the auxiliary-reagent 144 is an activator which activates thekey-reagent 142 once the auxiliary-reagent 144 is mixed with thewater-sample. Both reagents 142, 144 can alternatively be arrangedbetween the measuring section 28 and the pump opening 40.

The sample-line 20 is provided with an absorption body 146 which is afleece body and is arranged between the measuring section 28 and thepump opening 40. The sample-line 20 is provided with a dose capillary148 adjacent to the inlet opening 22. Adjacent to the pump opening 40,the sample-line 20 can be provided with a stopper capillary 150 whichprevents any leakage out of the sample-line 20. The sample-line 20 isalso provided with a sample filter 152 between the inlet opening 23 andthe measuring section 28, and in particular close to the inlet opening23, to filter the sucked water-sample.

FIG. 10 shows, as an example, a cross section of the test-element 140 ofFIG. 9. The test-element 140 comprises basically two parts: a plasticbottom part 150 which is made by injection die-casting and a separatecover part 152 which is a clear-transparent plastic film adhered orwelded to the bottom part. The bottom part 150 is, in the cross section,provided with a U-shaped sample-line groove 21 which is closed by thecover part 152. In this way, the bottom part 150 and the cover part 152form the sample-line 20.

The present invention is not limited to embodiments described herein;reference should be had to the appended claims.

What is claimed is:
 1. A basic unit for a mobile water analyzing system,the basic unit comprising: a photometer comprising a light sourceconfigured to generate a measurement beam and a light detectorconfigured to receive the measurement beam; a test element receptacleconfigured so as to allow a separate test element comprising a measuringsection and a pump port to be inserted into the test element receptacle:a photometric measuring track, the photometric measuring track beingdefined by the measuring section when the separate test element isinserted into the test element receptacle, the measurement beam and thephotometric measuring track being aligned during a photometricmeasurement so that a photometric measurement occurs along alongitudinal length of each of the photometric measuring track and themeasuring section; and a pump actuator cooperatively connected with thepump port.
 2. The basic unit as recited in claim 1, further comprisingat least one contact, wherein the separate test element furthercomprises at least one contact and at least one electrode which isarranged in the measuring section, wherein the at least one electrode ofthe separate test element is configured to connect with the photometervia the at least one contact of the basic unit and the at least onecontact of the separate test element.
 3. The basic unit as recited inclaim 1, wherein the separate test element further comprises a sampleline, and the photometric measuring track is formed by a longitudinalsection of the sample line.
 4. The basic unit as recited in claim 1,wherein the basic unit further comprises at least one of a heatingelement configured to heat the separate test element and a coolingelement configured to cool the separate test element.
 5. A test elementfor a mobile water analyzing system, the test element comprising: asample line comprising: an inlet opening disposed at a first end, theinlet opening being configured to receive a water sample, a pump portdisposed at a second end of the sample line, an inlet section disposedbetween the inlet opening and the pump port, and a measuring sectioncomprising at least one window arranged at an end of the measuringsection, the measuring section being arranged between the inlet sectionand the pump port and being coincident with a sample pathway; and a keyreagent disposed in the sample line.
 6. The test element as recited inclaim 5, wherein the sample line is a microfluidic sample line.
 7. Thetest element as recited in claim 5, further comprising a bottom part anda separate cover part, the bottom part and the separate cover part beingarranged so as to form the sample line therebetween.
 8. The test elementas recited in claim 5, further comprising at least one contact, and atleast one electrode arranged in the measuring section, wherein the atleast one electrode is configured to connect with an analyzer via the atleast one contact and via at least one contact of a separate basic unit.9. The test element as recited in claim 5, wherein the measuring sectionis formed by a longitudinal section of the sample line.
 10. The testelement as recited in claim 5, further comprising a pump membraneconfigured to be controlled by a pump actuator.
 11. The test element asrecited in claim 10, wherein the pump actuator is a part of a samplepump of a separate basic unit, the sample pump being connected with thepump port.
 12. The test element as recited in claim 5, wherein the testelement further comprises an auxiliary reagent disposed in the sampleline, the auxiliary reagent being disposed between the key reagent andthe pump port.
 13. The test element as recited in claim 5, wherein testelement further comprises an absorption body disposed between themeasuring section and the pump port.
 14. The test element as recited inclaim 5, wherein test element further comprises a sample filter disposedin the inlet section.
 15. The test element as recited in claim 5,wherein test element further comprises a hydrophobic stopper capillarydisposed in the sample line.
 16. The test element as recited in claim 5,wherein test element further comprises a dose capillary disposed in thesample line.
 17. The test element as recited in claim 5, wherein testelement is prefabricated.